Unix socket support in the standard library #1479

sfackler · Jan 26, 2016

alexcrichton · Jan 26, 2016

alexcrichton reviewed Jan 26, 2016

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alexcrichton · Jan 26, 2016

text/0000-unix-socket.md

+is more accurate but weirdly repetitive and the extension trait module
+`std::os::linux::unix` is even weirder. `std::os::unix::socket` is an option,
+but seems like too general of a name for specifically `AF_UNIX` sockets as
+opposed to *all* sockets.


Perhaps another unresolved question for now could be whether Windows named pipes should be added in parallel? Or something along the lines of if we should hold off on stabilization until there's a suitable Windows alternative as well.

I don't think that blocking this feature on named pipes makes a ton of sense. Named pipes do not appear to be used heavily in the Rust ecosystem, and I don't really want us to get into a habit of wanting to add platform specific feature X to the standard library and then hunting for a roughly comparable other-platform specific feature Y to implement along side it for "symmetry".

Hm ok, but I do also want to not tip the scales too far in favor of Unix as there are lots of abstractions on Windows we could reasonably provide (e.g. named pipes, IOCP bindings, etc). While crates today may not use these much it may just be because the Windows community is a little smaller.

These are mostly just musings, though, I'd be ok if the RFC doesn't explicitly mention named pipes.

alexcrichton · Jan 26, 2016

alexcrichton reviewed Jan 26, 2016

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alexcrichton · Jan 26, 2016

text/0000-unix-socket.md

+    /// This function will cause all pending and future I/O calls on the
+    /// specified portions to immediately return with an appropriate value
+    /// (see the documentation of `Shutdown`).
+    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {


This function isn't currently on UdpSocket, which I seem to recall is because it doesn't do much for datagram-oriented services, but do you know if it works well with Unix datagrams?

I think I probably just added it for completeness, but I'd expect it to bounce any pending recv calls at least. I'll see if it actually does anything.

It looks like shutdown does do what you'd expect for a datagram socket: rust-lang-nursery/unix-socket@63650be#diff-b4aea3e418ccdb71239b96952d9cddb6R1252

alexcrichton · Jan 26, 2016

alexcrichton reviewed Jan 26, 2016

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alexcrichton · Jan 26, 2016

text/0000-unix-socket.md

+Differences from `UdpSocket`:
+* `bind` takes an `AsRef<Path>` rather than a `ToSocketAddrs`.
+* The `unbound` method creates an unbound socket, as a Unix socket does not need
+  to be bound to send messages.


This method differs somewhat from the planned strategy of UdpSocket which is to perhaps introduce a UdpBuilder, but does this mean that an unbound UnixDatagram is useful in its own right for sending/receiving data?

It can't receive any data since you can't address it, but it can send: https://github.com/rust-lang-nursery/unix-socket/blob/master/src/lib.rs#L1159-L1173. This was added explicitly in a PR, so I believe it's a thing that's used in practice: rust-lang-nursery/unix-socket#14

Hm ok, seems reasonable to at least come in as unstable-to-start-out-with

alexcrichton · Jan 26, 2016

alexcrichton reviewed Jan 26, 2016

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alexcrichton · Jan 26, 2016

text/0000-unix-socket.md

+
+While there is precedent for platform specific components in the standard
+library, this will be the by far the largest platform specific addition.
+


One drawback that may want to be mentioned here is the lack of a smooth migration path from unix-socket to the standard library. For example users of Unix sockets will currently have to decide whether to support older versions of Rust (and use unix-socket) or newer versions (use std::os::unix::net). Additionally, we'll have to duplicate the code when unix-socket is compiled against a standard library that also has Unix sockets.

We have ideas for implementing such a migration path, but none of these ideas have an RFC or have been implemented.

I'm not particularly worried about this specific case - there's not all that much code and these kinds of objects aren't typically going to be passed around between crates like Durations might be.

The migration path ideas we've had seem to me to be a bit like the ideas to store fully elaborated source on crates.io - probably never going to happen :).

DemiMarie · Feb 1, 2016

DemiMarie reviewed Feb 1, 2016

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DemiMarie · Feb 1, 2016

text/0000-unix-socket.md

+Unix sockets can be configured with the `SOCK_STREAM`, `SOCK_DGRAM`, and
+`SOCK_SEQPACKET` types. `SOCK_STREAM` creates a connection-oriented socket that
+behaves like a TCP socket, `SOCK_DGRAM` creates a packet-oriented socket that
+behaves like a UDP socket, and `SOCK_SEQPACKET` provides something of a hybrid


SOCK_DGRAM Unix sockets are reliable.

alexcrichton · Mar 3, 2016

🔔 This RFC is now entering its week-long final comment period 🔔

alexcrichton · Mar 3, 2016

Also from discussion in triage yesterday, the libs team concluded that a good way forward for now with abstract sockets is to do something like:

Validate no nul bytes are found in strings
Perhaps eventually add a linux-specific extension trait to manage abstract sockets.

It at least errs on the side of being conservative for now!

sfackler · Mar 4, 2016

Updated to disallow use of the abstract namespace.

gkoz · Mar 7, 2016

Shouldn't there be a way to set permissions on the socket before starting to listen to it?

sfackler · Mar 7, 2016

What libc API would that use? According to the man page, the socket will inherit the permissions of the directory it's defined in on Linux, but filesystem permissions are ignored on BSD: http://man7.org/linux/man-pages/man7/unix.7.html#NOTES

gkoz · Mar 7, 2016

I had chmod in mind ;) Okay, while I doubt any modern BSDs ignore "file" permissions I totally missed that the portable way is to rely on directory-level permissions.

alexcrichton · Mar 17, 2016

The libs team discussed this RFC during triage yesterday, an the decision was to merge. This was the original intention for how Unix sockets would reenter the standard library and the unix-socket crate is doing well enough that moving it in almost wholesale seems good at this time (it's quickly becoming a vetted API).

Thanks again for the RFC @sfackler!

Tracking issue: rust-lang/rust#32312

alexcrichton · Mar 17, 2016

Ah, also, the initial implementation: rust-lang/rust#32302

sfackler added the T-libs label Jan 26, 2016

sfackler self-assigned this Jan 26, 2016

Unix socket support in the standard library

3f0c85b

sfackler force-pushed the sfackler:unix-socket branch from 4eaf358 to 3f0c85b Jan 27, 2016

alexcrichton added the final-comment-period label Mar 3, 2016

Update to disallow abstract namespaces

2dd9b01

maghoff and others added some commits Mar 7, 2016

Fix typo

dcafbc1

Merge pull request #1 from maghoff/patch-1
Fix typo

97780a7

alexcrichton referenced this pull request Mar 17, 2016
Closed
Tracking issue for Unix Sockets in the standard library #32312

alexcrichton merged commit 97780a7 into rust-lang:master Mar 17, 2016

Centril added A-net A-platform A-types-libstd labels Nov 23, 2018

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Unix socket support in the standard library #1479

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sfackler commented Jan 26, 2016

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Centril added A-net A-platform A-types-libstd labels Nov 23, 2018

alexcrichton reviewed Jan 26, 2016

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alexcrichton reviewed Jan 26, 2016

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alexcrichton reviewed Jan 26, 2016

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alexcrichton reviewed Jan 26, 2016

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sfackler force-pushed the sfackler:unix-socket branch from `4eaf358` to `3f0c85b` Jan 27, 2016

DemiMarie reviewed Feb 1, 2016

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alexcrichton merged commit `97780a7` into rust-lang:master Mar 17, 2016